1. Field of the Invention
This invention relates to a general-purpose electromagnetic contactor, and more particularly to an improved electromagnetic contactor without arc generation wherein the prior art silver contacts are eliminated due to the improvement of the contact portions between the fixed terminals and a movable piece, thereby allowing the semi-conductor to separate completely from the power supply under an open-circuit condition.
2. Description of the Prior Art
It has been well-known in the art that contacts are subjected to corrosion and abrasion due to the generation of an arc to which ionizes the air between the contacts during the breaking of current, in the conventional electromagnetic contactor.
Specifically, in order to prevent the corrosion or dissolution of the contact material due to the generation of an arc through a current caused by the ionized gas between contacts, a triac is connected between the supply terminal and the load terminal in parallel, and a separate gate terminal is provided to connect them asynchronously, thereby preventing arc generation.
A number of arc-generation preventing apparatus have been proposed for protecting contacts by employing a semi-conductor device, as disclosed in U.S. Pat. Nos. 3,555,353, 3,558,910, and 3,736,446; Japanese laid-open Publication Nos. Sho 49-745, 51-118056, 52-122853 and 53-110432; and Korean Patent Application No. 84-5220 field by the inventor of the present invention. However, most of these apparatus have a drawback in that since an electric circuit provided among the power supply, the control device and the load relies on the function of breaking the inner inverse voltage thereof only, the sudden flow of power occurs between the power supply and the load if the inner voltage of the semi-conductor device is broken down due to an opening or closing operation of the power supply, thunderbolt, etc. Therefore, said apparatus did not overcome the above-mentioned problem in security and thus failed to reach the stage of practical utilization.